Dynamic mechnical properties of unfilled and glass fiber filled liquid crystal polyester (LCP) have been investigated in the temperature range from -100° to 250°C. Two transitions, atTgandTβ, were observed with decreasing temperature, whereTgis the glass transition of the samples; however, the origin ofTβis unknown. Both LCP and LCP composites exhibit strong dynamic mechanical anisotropy with respect to the molding flow direction. As the glass fiber content increases, the reinforcing effect is improved due to the increase in the effective storage modulus, while the modulus anisotropy is reduced.